Permeated grooving in cmp polishing pads

ABSTRACT

A polishing pad for polishing a semiconductor wafer or other materials, having grooves in the polishing pad to enhance the usable lifetime of the polishing pad.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Nonprovisional patentapplication Ser. No. 14/029,863, filed Sep. 18, 2013, the contents ofwhich are herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of chemicalmechanical polishing (CMP). More particularly, a CMP polishing padhaving grooves arranged to improve polishing pad lifetime.

BACKGROUND OF THE INVENTION

In the fabrication of integrated circuits and other electronic devices,multiple layers of conducting, semiconducting and dielectric materialsare deposited onto and removed from a surface of a semiconductor wafer.Thin layers of conducting, semiconducting and dielectric materials maybe deposited using a number of deposition techniques. Common depositiontechniques in modem wafer processing include physical vapor deposition(PVD), also known as sputtering, chemical vapor deposition (CVD),plasma-enhanced chemical vapor deposition (PECVD) and electrochemicalplating, among others. Common removal techniques include wet and dryisotropic and anisotropic etching, among others.

As layers of materials are sequentially deposited and removed, theuppermost surface of the wafer becomes non-planar. Because subsequentsemiconductor processing (e.g., metallization) requires the wafer tohave a flat surface, the wafer needs to be planarized. Planarization isuseful for removing undesired surface topography and surface defects,such as rough surfaces, agglomerated materials, crystal lattice damage,scratches and contaminated layers or materials.

Chemical mechanical planarization, or chemical mechanical polishing(CMP), is a common technique used to planarize work pieces such assemiconductor wafers. In conventional CMP, a wafer carrier, or polishinghead, is mounted on a carrier assembly. The polishing head holds thewafer and positions the wafer in contact with a polishing layer of apolishing pad within a CMP apparatus. The carrier assembly provides acontrollable pressure between the wafer and polishing pad.Simultaneously therewith, a slurry, or other polishing medium, is flowedonto the polishing pad and into the gap between the wafer and polishinglayer. To effect polishing, the polishing pad and wafer are moved,typically rotated, relative to one another. The wafer surface ispolished and made planar by chemical and mechanical action of thepolishing layer and polishing medium on the surface. As the polishingpad rotates beneath the wafer, the wafer sweeps out a typically annularpolishing track, or polishing region, wherein the wafer surface directlyconfronts the polishing layer.

Important considerations in designing a polishing layer include thedistribution of polishing medium across the face of the polishing layer,the flow of fresh polishing medium into the polishing track, the flow ofused polishing medium from the polishing track and the amount ofpolishing medium that flows through the polishing zone essentiallyunutilized, among others. One way to address these considerations is toprovide the polishing layer with grooves. Over the years, quite a fewdifferent groove patterns and configurations have been implemented.Prior art groove patterns include radial, concentric-circular,Cartesian-grid, straight line, random and spiral, patterns among others.Prior art groove configurations include configurations wherein the depthof all the grooves are uniform among all grooves and configurationswherein the depth of the grooves varies from one groove to another.

It is generally acknowledged among CMP practitioners that certain groovepatterns and depths result in higher slurry consumption and shorterpolishing pad life than others to achieve comparable material removalrates. Circular grooves, which do not connect to the outer periphery ofthe polishing layer, tend to consume less slurry than radial grooves,which provide the shortest possible path for slurry to reach the padperimeter under the centrifugal forces resulting from the rotation ofthe pad. Cartesian grids of grooves, which provide paths of variouslengths to the outer periphery of the polishing layer, hold anintermediate position.

Various groove patterns have been disclosed in the prior art thatattempt to reduce slurry consumption and maximize slurry retention timeon the polishing layer. For example, U.S. Pat. No. 6,241,596 toOsterheld et al. discloses a rotational-type polishing pad havinggrooves defining zigzag channels that generally radiate outward from thecenter of the pad. In one embodiment, the Osterheld et al. pad includesa rectangular “x-y” grid of grooves. The zigzag channels are defined byblocking selected ones of the intersections between the x- andy-direction grooves, while leaving other intersections unblocked. Inanother embodiment, the Osterheld et al. pad includes a plurality ofdiscrete, generally radial zigzag grooves. Generally, the zigzagchannels defined within the x-y grid of grooves or by the discretezigzag grooves inhibit the flow of slurry through the correspondinggrooves, at least relative to an unobstructed rectangular x-y grid ofgrooves and straight radial grooves. Another prior art groove patternthat has been described as providing increased slurry retention time isa spiral groove pattern that is assumed to push slurry toward the centerof the polishing layer under the force of pad rotation.

Consumables are the highest cost in CMP processing. Topping the listbehind slurries are CPM polishing pads which are replaced when the padwears to the point that the polish process becomes compromised. There isa need for a polishing pad that has an extended life over currentpolishing pads.

SUMMARY OF THE INVENTION

The following presents a simplified summary in order to provide a basicunderstanding of one or more aspects of the invention. This summary isnot an extensive overview of the invention, and is neither intended toidentify key or critical elements of the invention, nor to delineate thescope thereof. Rather, the primary purpose of the summary is to presentsome concepts of the invention in a simplified form as a prelude to amore detailed description that is presented later.

In accordance with an embodiment of the present invention, a CMPpolishing pad is provided. The CMP polishing pad, comprises: a CMPpolishing layer, including a polishing pad configured to polish asurface of at least one of a magnetic, optical or semiconductorsubstrate in the presence of a polishing medium, the polishing layerincluding a rotational axis, an outer periphery and an annular polishingtrack concentric with the rotational axis, wherein the polishing pad hasa top surface, a bottom surface and a thickness; a plurality of groovesformed in the polishing pad comprising first and second sets of grooveslocated entirely within the polishing pad; the first set of grooveslocated on the top surface of the polishing pad, has a pattern andvertically penetrates into the top surface of polishing pad to at least50% of the polishing pad thickness; and the second set of grooves islocated on the bottom surface of the polishing pad, has a patternidentical to the pattern of the first set of grooves and verticallypenetrates into the bottom surface of polishing pad to at least 50% ofthe polishing pad thickness; and wherein the first set of grooves islocated between and interlaced at the interior ends, without anyintersections between the first and second set of grooves, and areconfigured to present a continuous groove to the material being polishedfrom the top of the pad to within 6 percent of the bottom of thepolishing pad.

In accordance with another embodiment of the present invention, a CMPpolishing pad is provided. The CMP polishing pad, comprises: a CMPpolishing layer, including a polishing pad configured to polish asurface of at least one of a magnetic, optical or semiconductorsubstrate in the presence of a polishing medium, the polishing layerincluding a rotational axis, an outer periphery and an annular polishingtrack concentric with the rotational axis, wherein the polishing pad hasa top surface, a bottom surface and a thickness; a plurality of groovesformed in the polishing pad comprising first, second and third sets ofgrooves located entirely within the polishing pad; the first set ofgrooves located on the top surface of the polishing pad, has a patternand vertically penetrates into the top surface of polishing pad to atleast 37% of the polishing pad thickness; the second set of grooves islocated on the bottom surface of the polishing pad, has a patternidentical to the pattern of the first set of grooves and verticallypenetrates into the bottom surface of polishing pad to at least 37% ofthe polishing pad thickness; and wherein the first set of grooves islocated in direct alignment at the interior ends, with the second set ofgrooves; and the third set of grooves is centered between the topsurface of the polishing pad and the bottom surface of the polishing padand located between and interlaced with the aligned interior ends of thefirst and second groves, and are configured to present a continuesgroove to the material being polished from the top of the pad to within6 percent of the bottom of the polishing pad.

In accordance with a further embodiment of the present invention, apolishing pad is provided. The polishing pad, comprising: a polishinglayer configured to polish a surface of at least one of a magnetic,optical or semiconductor substrate in the presence of a polishingmedium, the polishing layer including: a rotational axis; an outerperiphery; an annular polishing track concentric with the rotationalaxis; and a peripheral region located between the annular polishingtrack and the outer periphery; and a plurality of grooves formed in thepolishing layer, having top and bottom surfaces, and comprising: theplurality of grooves formed in the polishing pad comprising first andsecond sets of grooves located entirely within the polishing pad; thefirst set of grooves located on the top surface of the polishing pad,has a pattern and vertically penetrates into the top surface ofpolishing pad to at least 50% of the polishing pad thickness; and thesecond set of grooves is located on the bottom surface of the polishingpad, has a pattern identical to the pattern of the first set of groovesand vertically penetrates into the bottom surface of polishing pad to atleast 50% of the polishing pad thickness; and wherein the first set ofgrooves is located between and interlaced at the interior ends, withoutany intersections between the first and second set of grooves, and areconfigured to present a continues groove to the material being polishedfrom the top of the pad to within 6 percent of the bottom of thepolishing pad.

In accordance with a further embodiment of the present invention, apolishing pad is provided. The polishing pad, comprising: a polishinglayer configured to polish a surface of at least one of a magnetic,optical or semiconductor substrate in the presence of a polishingmedium, the polishing layer including: a rotational axis; an outerperiphery; an annular polishing track concentric with the rotationalaxis; and a peripheral region located between the annular polishingtrack and the outer periphery; and a plurality of grooves formed in thepolishing layer, having top and bottom surfaces, and comprising: theplurality of grooves formed in the polishing pad comprising first,second and third sets of grooves located entirely within the polishingpad; the first set of grooves located on the top surface of thepolishing pad, has a pattern and vertically penetrates into the topsurface of polishing pad to at least 37% of the polishing pad thickness;the second set of grooves is located on the bottom surface of thepolishing pad, has a pattern identical to the pattern of the first setof grooves and vertically penetrates into the bottom surface ofpolishing pad to at least 37% of the polishing pad thickness; andwherein the first set of grooves is located in direct alignment at theinterior ends, with the first set of grooves; and the third set ofgrooves is centered between the top surface of the polishing pad and thebottom surface of the polishing pad and located between and interlacedwith the aligned interior ends of the first and second groves, and areconfigured to present a continues groove to the material being polishedfrom the top of the pad to within 6 percent of the bottom of thepolishing pad.

DESCRIPTION OF THE VIEWS OF THE DRAWING

FIG. 1 is a partial perspective view of a chemical mechanical polishing(CMP) system of the present invention;

FIG. 2 is a plan view of the polishing pad of FIG. 1;

FIG. 3 is an illustration of a typical polishing pad of the presentinvention;

FIG. 3a is an illustration of a typical polishing pad worn to the pointthat the polish process has become compromised;

FIGS. 4 and 5 show the cross-section of polishing pads in accordancewith embodiments of the present invention.

In the drawings, like reference numerals are sometimes used to designatelike structural elements. It should also be appreciated that thedepictions in the figures are diagrammatic and not to scale.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The present invention is described with reference to the attachedfigures. The figures are not drawn to scale and they are provided merelyto illustrate the invention. Several aspects of the invention aredescribed below with reference to example applications for illustration.It should be understood that numerous specific details, relationships,and methods are set forth to provide an understanding of the invention.One skilled in the relevant art, however, will readily recognize thatthe invention can be practiced without one or more of the specificdetails or with other methods. In other instances, well-known structuresor operations are not shown in detail to avoid obscuring the invention.The present invention is not limited by the illustrated ordering of actsor events, as some acts may occur in different orders and/orconcurrently with other acts or events. Furthermore, not all illustratedacts or events are required to implement a methodology in accordancewith the present invention.

Referring now to the drawings, FIG. 1 shows in accordance with thepresent invention a chemical mechanical polishing (CMP) system, which isgenerally denoted by the numeral 100. CMP system 100 includes apolishing pad 104 having a polishing layer 108 that includes a pluralityof grooves 112 arranged and configured for improving the utilization ofa polishing medium 116 applied to the polishing pad during polishing ofa semiconductor wafer 120 or other work pieces, such as glass, siliconwafers and magnetic information storage disks, among others. Forconvenience, the term “wafer” is used in the description below. However,those skilled in the art will appreciate that work pieces other thanwafers are within the scope of the present invention. Polishing pad 104and its unique features are described in detail below.

CMP system 100 may include a polishing platen 124 rotatable about anaxis 128 by a platen driver (not shown). Platen 124 may have an uppersurface on which polishing pad 104 is mounted. A wafer carrier 132rotatable about an axis 136 may be supported above polishing layer 108.Wafer carrier 132 may have a lower surface that engages wafer 120. Wafer120 has a surface 140 that confronts polishing layer 108 and isplanarized during polishing. Wafer carrier 132 may be supported by acarrier support assembly (not shown) adapted to rotate wafer carrier 132and attached wafer 120 and provide a downward force F to press wafersurface 140 against polishing layer 108 so that a desired pressureexists between the wafer and the polishing layer during polishing.

CMP system 100 may also include a supply system for supplying polishingmedium 116 to polishing layer 108. Supply system may include a reservoir(not shown), e.g., a temperature controlled reservoir, that holdspolishing medium 116. A conduit 148 may carry polishing medium 116 fromthe reservoir to a location adjacent polishing pad 104 where thepolishing medium is dispensed onto polishing layer 108. A flow controlvalve (not shown) may be used to control the dispensing of polishingmedium 116 onto pad 104.

During the polishing operation, the platen driver rotates platen 124 andpolishing pad 104 and the supply system is activated to dispensepolishing medium 116 onto the rotating polishing pad. Polishing medium116 spreads out over polishing layer 108 due to centrifugal force causedby the rotation of polishing pad 104, including the gap between wafer120 and polishing pad 104. The wafer carrier 132 may be rotated at aselected speed, e.g., 0 rpm to 150 rpm, so that wafer surface 140 movesrelative to the polishing layer 108. The wafer carrier 132 may also becontrolled to provide a downward force F so as to induce a desiredpressure, e.g., 0 psi to 15 psi, between wafer 120 and polishing pad104. Polishing platen 124 is typically rotated at a speed of 0 to 150rpm. As polishing pad 104 is rotated beneath wafer 120, surface 140 ofthe wafer sweeps out a typically annular wafer track, or polishing track152 on polishing layer 108.

It is noted that under certain circumstances polishing track 152 may notbe strictly annular. For example, if surface 140 of wafer 120 is longerin one dimension than another and the wafer and polishing pad 104 arerotated at particular speeds such that these dimensions are alwaysoriented the same way 152 would be generally annular, but have a widththat varies from the longer dimension to the shorter dimension. Asimilar effect would occur at certain rotational speeds if surface 140of wafer 120 were bi-axially symmetric, as with a circular or squareshape, but the wafer is mounted off-center relative to the rotationalcenter of that surface. Yet another example of when polishing track 152would not be entirely annular is when wafer 120 is oscillated in a planeparallel to polishing layer 108 and polishing pad 104 is rotated at aspeed such that the location of the wafer due to the oscillationrelative to the polishing layer is the same on each revolution of thepad. In all of these cases, which are typically exceptional, polishingtrack 152 is still annular in nature, such that they are considered tofall within the coverage of the term “annular”.

FIG. 2 illustrates polishing pad 104 of FIG. 1 in more detail. Spiralgrooves 112 are arranged within polishing track 152 for illustrationpurposes only. Groves may be radial, concentric-circular,Cartesian-grid, straight line, random or spiral patterns, among othersso that they are spaced from one another in both a radial direction 156and a circumferential direction relative to the rotational nature ofpolishing pad 104. During polishing, the polishing medium, e.g.,polishing medium 116 of FIG. 1, moves from groove to groove withinpolishing track 152 (as illustrated by arrows 164) primarily only underthe influence of wafer 120 as the wafer is rotated in confrontingrelationship with polishing pad 104, e.g., in rotational direction 166.Since the polishing medium generally moves only when wafer 120 ispresent, the polishing medium tends to be utilized more efficiently withconventional pads, having grooves that extend uninterrupted through thepolishing track. This is so because a polishing medium often flowsthrough the polishing track in these uninterrupted grooves under thecentrifugal influence of the rotation of the pad regardless of whetheror not the wafer is present.

In addition to grooves 112 being spaced from one another radially andcircumferentially, it is desirable that at least a portion of thelongitudinal axis 168 of each groove be oriented non-circumferentiallyrelative to polishing pad 104. In other words, it is desirable thatlongitudinal axes 168 of grooves 112 not be merely arcs of circlesconcentric with rotational axis 128 of polishing pad 104. Providing suchgrooves 112 can facilitate the flow of a polishing medium as polishingpad 104 is rotated due to the effects of centrifugal forces caused bythe rotation. In the present example, grooves 112 are generally arcs ofspirals and, therefore, are non-circumferential along their entirelengths. In some, but not necessarily all, groove arrangements of thepresent invention, it is desirable that the distance between endpointsof each groove along a straight line connecting the endpoints be lessthan the least dimension of the surface of the substrate being polishedthat extends through the rotational center of that surface. For example,for a circular surface rotated about its concentric center, thestraight-line distance between the endpoints of each groove using thiscriterion would be a value less than the diameter of the surface. On theother hand, for a rectangle having long sides of length L and shortsides of length S, under this criterion the straight line distancebetween the endpoints of a groove would be a value less than the shortside length S.

Grooves 112 may also include a subset 172 located partially in a centralregion 176 of polishing layer 108 radially inward of polishing track 152and partially in the polishing track. This subset 172 of grooves 112 isuseful, e.g., in the context of polishing systems, such as CMP system100 of FIG. 1, in which a polishing medium is dispensed into centralregion 176, for enhancing the flow of the polishing medium from thecentral region into polishing track 152. In addition, grooves 112 mayinclude a subset 180 of grooves that extend from polishing track 152 toa peripheral region 184 (if any) radially outward of the polishingtrack. Grooves 112 in subset 180 may also extend to the peripheral edge188 of polishing pad 104, if desired. Subset 180 of grooves 112 isuseful, e.g., for enhancing the flow of the polishing medium out ofpolishing track 152.

In general CMP processes use a thin polishing pad in the range of 80 to120 thousandths of an inch (mils) that can be mated with a sub pad.Grooves are manufactured into the pad providing a delivery path forfresh slurry and an exit path for the process effluent, wherein thegrooves can be machined by a laser or by mechanical means. When the padwears thin and grooves become shallow, the delivery and exit pathsbecome compromised resulting in lower removal rates, thus decreasingthroughput. Shallow pad grooves can cause other issues such as increaseddefectivity and increased non-uniformity.

A CMP polishing pad is typically a circular disc. The polishing pad istypically composed of a material selected from a group comprised of apolyurethane, a polycarbonate, a nylon, an acrylic polymer, or apolyester. A CMP polishing pad may or may not have a sub pad.

As will become readily apparent from FIG. 3, grooves 112 may have any ofa wide variety of arrangements and configurations. Here the grooves areshown of a depth approximately equal to 37.5% of the pad thickness or 30mils in an 80 mil pad, wherein the cross sectional shape of the groovesas rectangular. While these represent preferred embodiments, both thedepth of the grooves and their cross-sectional shapes can differ fromthe figure, and can vary within a given pad. The polishing pad groovescan be between 14 and 30 mils wide and the shape of the grooves can berectangular.

The topographical surface arrangement of the grooves can vary dependingon the processing equipment and the material being polished. Surfacepatterns can be chosen from a group comprised of radial,concentric-circular, Cartesian-grid, straight line, random or spiralpatterns,

When the polishing pad wears thin and grooves become shallow as shown inFIG. 3a , the delivery and exit paths become compromised resulting inlower removal rates, thus decreasing throughput. Shallow pad grooves cancause other issues such as increased defectivity and increasednon-uniformity. Typically, the polishing pad must be replaced when aminimum of 5 mils of the grooves 112 are remaining.

However, in FIG. 2 grooves 112 are arranged end-to-end in groups 192 sothat the grooves in each group extend along a corresponding smooth path,in this case a spiral path 194, that extends from central region 176,through polishing track 152 and to peripheral edge 188. As those skilledin the art will appreciate, groups 192 of grooves 112 may be arranged ina radial, concentric-circular, Cartesian-grid, straight line, random orspiral patterns, among others in a similar manner, wherein the shapesand orientations, are angled into or away from the design rotationaldirection 198 of polishing pad 104, circularly arced and generallyradial into or away from the design rotational direction 198 ofpolishing pad 104, circularly arced and generally radial, circularlyarced and non-radial, among many others.

The purpose of the present invention is to manufacture pads with groovesthrough the entire thickness of the polish pad, allowing significantlymore of the pad to be consumed. Overlap between the grooves ensures thattransition.

FIG. 4 shows a first embodiment of the present invention. The CMPpolishing pad has 2 sets of grooves that exceed 50% of the pad thicknesson both the top and bottom surface of the pad wherein the top and bottomgrooves are interlaced at the interior ends and present a continuesgroove to the material being polished from the top of the pad to within6 percent of the bottom of the polishing pad where Shallow pad groovescan cause other issues such as increased defectivity and increasednon-uniformity

Current pad usage of a typical pad before replacement of the pad isrequired is about 30% wherein usage of the pad disclosed in the presentinvention is 91% or 3 to 1 increase in pad life time.

FIG. 5 shows a second embodiment of the present invention. The CMPpolishing pad has 3 sets of grooves that exceed 37% of the pad thicknesson both the top and bottom surfaces of the pad and the center of thepad, and wherein the top and bottom grooves are directly in line at theinterior ends and the center grooves are centered between the top andbottom surfaces of the pad and interlaced at the interior ends of thetop and bottom grooves and present a continues groove to the materialbeing polished from the top of the pad to within 6 percent of the bottomof the polishing pad where Shallow pad grooves can cause other issuessuch as increased defectivity and increased non-uniformity.

Multiple grooving methods such as grooving from the back side of thepad, mid-pad manufacturing process grooving, multiple pad layers,molding, and 3D printing could be employed to achieve the disclosed padgrooving.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only and not limitation. Numerous changes to the disclosedembodiments can be made in accordance with the disclosure herein withoutdeparting from the spirit or scope of the invention. Thus, the breadthand scope of the present invention should not be limited by any of theabove described embodiments. Rather, the scope of the invention shouldbe defined in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A CMP polishing pad, comprising: a CMP polishinglayer, including a polishing pad configured to polish a surface of atleast one of a magnetic, optical or semiconductor substrate in thepresence of a polishing medium, the polishing layer including arotational axis, an outer periphery and an annular polishing trackconcentric with the rotational axis, wherein the polishing pad has a topsurface, a bottom surface and a thickness between the top surface andthe bottom surface; a plurality of grooves formed in the polishing padcomprising first and second sets of grooves located entirely within thepolishing pad; the first set of grooves located on the top surface ofthe polishing pad, has a pattern and all grooves in the top surfacevertically penetrate into the top surface of polishing pad to at least50% of the polishing pad thickness; and the second set of grooves islocated on the bottom surface of the polishing pad and all grooves ofthe bottom surface vertically penetrate into the bottom surface ofpolishing pad to at least 50% of the polishing pad thickness; andwherein the first set of grooves is located between and interlaced atthe interior ends with the second set of grooves, without anyintersections between the first and second set of grooves, and areconfigured to present a continuous groove to the material being polishedfrom the top of the pad to within 6 percent of the bottom of thepolishing pad.
 2. The CMP polishing pad of claim 1, wherein thepolishing pad is composed of a material selected from the groupcomprising: a polyurethane, a polycarbonate, a nylon, an acrylicpolymer, or a polyester.
 3. The CMP polishing pad of claim 1, whereinthe polishing pad pattern is selected from the group comprising: radial,concentric-circular, Cartesian-grid, straight line, random or spiralpatterns.
 4. A polishing pad, comprising: a polishing layer configuredto polish a surface of at least one of a magnetic, optical orsemiconductor substrate in the presence of a polishing medium, thepolishing layer including: a rotational axis; an outer periphery; anannular polishing track concentric with the rotational axis; andperipheral region located between the annular polishing track and theouter periphery; and a plurality of grooves formed in the polishinglayer, having top and bottom surfaces, and comprising: the plurality ofgrooves formed in the polishing pad comprising first and second sets ofgrooves located entirely within the polishing pad; the first set ofgrooves located on the top surface of the polishing pad, has a patternand each of the grooves in the first set of grooves verticallypenetrates into the top surface of polishing pad to at least 50% of thepolishing pad thickness; and the second set of grooves is located on thebottom surface of the polishing pad and each of the grooves in thesecond set of grooves vertically penetrates into the bottom surface ofpolishing pad toward the top surface to at least 50% of the polishingpad thickness; and wherein the first set of grooves is located betweenand interlaced at the interior ends with the second set of grooves,without any intersections between the first and second set of grooves,and are configured to present a continues groove to the material beingpolished from the top of the pad to within 6 percent of the bottom ofthe polishing pad.
 5. The polishing pad of claim 4, wherein thepolishing pad is composed of a material selected from the groupcomprising: a polyurethane, a polycarbonate, a nylon, an acrylicpolymer, or a polyester.
 6. The polishing pad of claim 4, wherein thepolishing pad pattern is selected from the group comprising: radial,concentric-circular, Cartesian-grid, straight line, random or spiralpatterns.